Start control device for fluorescent lamps



F. MULLER May 24, 1960 START CONTROL DEVICE FOR FLUORESCENT LAMPS FiledSept. 16, 1959 Unit d S at s Paten ,9

START CONTROL DEVICE FOR FLUORESCENT LAMPS Ferdinand Miiller,Berlin-Charlottenburg, Germany, as-

signor to Siemens-Schuckertwerke Aktiengesellschaft, Berlin, Germany, acorporation of Germany Filed Sept. 16, 1959, Ser. No. 840,388 Claimspriority, application Germany Sept. 19, 1958 14 Claims. (Cl. 315-100) Myinvention relates to a start control device for fluorescent lamps,particularly those of the hot-cathode type, and will be describedhereinafter with reference to i in series with a conventionally employedglow-type starter for more rapidly starting the lamp. The circuitdiagram of Fig. 1 is of this type. Denoted by 1 and 2 are the twoterminals of a lighting fixture to be connected to analternating-current line. When the line voltage is switched on, thecurrent passes from terminal 2 through the heater-filament electrode 3of the fluorescent lamp 8, then serially through a rectifier diode 4 inthe forward direction and through the glow discharge gap of a starterswitch 5, then through the heater-filament electrode 6 and an inductiveballast 7 to the terminal 1. Due to the diode rectifier 4 in series withthe starter switch 5, the inductive ballast 7 is not traversed byalternating current but conducts half-wave current which reduces thevoltage drop across the ballast 7 in comparison with the voltage dropoccurring if an alternating voltage were impressed upon the ballast.This is because the halfwave current flowing through diode 4 and theinductive ballast 7 have an essential direct-current component, so thatthe iron-core of the ballast coil is constantly premagnetized a givenamount, and the ballast, therefore, cannot carry as large a voltage aswith alternating current.

The operation of the fixture is otherwise conventional. That is, whenvoltage is applied to terminals 1, 2 so that current passes through theheated electrodes 3, 6 and the glow discharge gap of starter switch 5,the bi-metal members of switch 5 becomes heated and the normallyseparated contacts enter into contact with each other. This causes acorrespondingly stronger current to flow through the heater helices 3and 6 whereby the discharge gap in the tubular lamp is pre-ionized to agreat extent. The closing of the contact in starter switch 5 eliminatesthe glow discharge. Hence the heating of the bi-metal members ceases sothat they cool gradually and have the increasing tendency to again openthe closed contacts. The resulting separation of the contactsinstantaneously interrupts the flow of current in the starter circuit.This produces at the inductive ballast coil 7 a corresponding voltagepeak 3 and 6 of the fluorescent lamp, whereafter the lamp continuesburning.

2,938,146 Patented May 24, 1960 essentially for elimination of radiointerference. In addition, an ohmic resistor 10 is connected parallel tothe diode 4. This resistor has a thermo-negative resistancecharacteristic (thermistor) for current-limiting purposes. If troubleoccurs in the starter circuit, for example if the contacts of thestarter switch 5 when initiating the ignition of the fluorescent lampremain closed beyond the normal interval of time, such prolonged closuremay cause damage to the installation because then the inductive ballast7 can carry an only small proportion of the voltage as long as therectifier diode is effective and hence, in this condition, cannotsufliciently limit the current in the starter circuit. The ballast,therefore, may be traversed continuously by an excessive amount ofcurrent which causes a detrimentally great amount of heating. However,the large continuous current also causes heating of the protectiveresistor 10 which then, by virtue of its temperature-dependentresistance and negative temperature coeflicient, increasingly forms ashunt for the diode 4 acting in the inverse direction of the diode. As aresult, a practically pure alternating current will eventually flowthrough the ballast 7, thus increasing its inductive impedance whichreduces the current to a harmless value.

It is an object of my invention to considerably sim plify the design ofa fluorescent lamp installation of the above-mentioned type, and to alsosimplify the assembling of such installation or fixture or the replacingof faulty components.

To this end, and in accordance with my invention, the starter switch andthe rectifier diode are disposed in the circuit, not as spaciallyindependent components, but in combined form, constituting a single unitor starter plug which occupies only slight total space and can beaccommodated as a single wiring component on or in the lighting fixtureor in the socket assembly for such fixture, if desired together with thethermistor in parallel to the rectifier and together with the capacitorin parallel to the starter switch proper. As a result, the expenditureand time involved in mounting and installing a fluorescent lightingfixture are reduced, and a number of further advantages are affordedtoward simplification in the design "of the auxiliary components and/orthe facility with which the circuit can be completed or repaired.

According to a more specific feature of my invention, the rectifierdiode, if desired together with the parallel thermistor, constitutes anindividually independent component or subassembly and has its ownhousing adapted to be mechanically joined with the starter switch toform therewith a single composite unit that can be inserted as a wholeinto the circuit or lighting fixture. In such a device, the rectifiersubassembly is preferably provided with channels for passingtherethrough the connecting wires leading to the starter switchsubassembly or to special contacts or terminals thereof. For example, aconnecting wire of the starter switch may be stuck through such achannel of the rectifier subassembly to be connected in that channel toan electric terminal con tact of the diode enclosed in the rectifierhousing and to {the parallel resistor, if the latter is enclosed in thesame housing. Such a channel may be formed by a metal sleeve to whichthe parts enclosed within the rectifier housing are electricallyconnected. One or more connecting wires may extend from these enclosedcomponents directly to the outside, or they may be connected toparticular terminal contacts of the rectifier housing.

The parallel capacitor for the starter switch may likewise form astructural unit or subassembly which can be put together with thestarter switch to form a single composite unit. However, according to analternative feature of the invention, the parallel capacitor for thestarter switch is combined with the rectifier and its parallel resistorto form a single structuralsubassembly together therewith. It is thenonly' necessary to simply connect the starter subassembly and thecomposite rectifier subassembly, and to permanently join these two bysoldering or clamping, in order to obtain a single component ready to bebuilt into the lighting fixture.

According to still another feature of my invention, the rectifierelement is disposed in the same housingthat accommodates the starterswitch. In this case, the rectifier element may be built into the samegas space as the starter switch, provided the type of rectifier is sochosen that no glow discharge can take place between its electrodes orat its p-n junction. For this purpose, the p-n junction, where itemerges at the surface of the semiconductor body of the diode, forexample a silicon rectifier, may be provided with a suitable protectivecoating of varnish or other insulating material to prevent glowdischarge.

According to still another feature of my invention, the housing of thestarter switch contains an additional enclosed chamber for accommodatingthe rectifier element. If desired, the additional chamber may be filledwith a protective gas, for example nitrogen, for increasing the servicelife of the rectifier element. The same additional chamber may enclosethe parallel thermistor for the rectifier diode.

Embodiments of start control devices according to the invention will bedescribed with reference to Figs. 2, 3 and 4 of the drawings,representing three such devices by way of example.

According to Fig. 2, the same gas space that contains the starter switchalso encloses the diode rectifier according to the circuit diagram ofFig. 1. Denoted by 11 is an insulating mounting base of the device, andby 12 a cup-shaped housing, for example of glass, which forms anenvelope for the gas space together with the base 11. The starter switchcomprises two bi-metal legs 13,14 which carry respective contacts 15 and16. Mounted in the gas space is a rectifier element 17, shown onlyschematically, which is connected into the circuit by means of twoconnecting wires 18 and 19. Three connecting wires 20, 2 1 and 22 leadfrom the enclosed components to the outside of the housing, althoughthese leads may also be connected to terminal contacts, for example,plug rings fastened to the mounting base 11. The unit thus formedcomprises a series connection of the starter switch and the rectifierdiode 4 in accordance with the circuit diagram shown in Fig. 1.

In the embodiment illustrated in Fig. 3, the mounting base 11 of thestarter device is fused or otherwise joined with the enclosing envelope12. The space sealed within the envelope is subdivided by a gas-tightpartition 25 into two chambers 25 and 24. Chamber 23 accommodates theabove-described parts 13 to 16 of the starter The housing of therectifier subassembly is denoted by 1 2.7. Two spring bodies 28, 29 arefirmly attached 'to'the switch, the reference numerals being inaccordance with those used in Fig. 2 for respectively similar elements.Mounted in chamber 24 are the diode element 17 and a thermistor 26 inparallel to the diode. The diode and thermistor are connected to wires18 and 19. The chamber 23 may be given a gaseous atmosphere particularlydesired for the gas discharge between the contacts of the starterswitch, whereas the chamber 24 is preferably provided with a difierentatmosphere, such as nitrogen, acting as a protective gas for therectifier element 17. Three connecting wires 20, 21 and 22 pass from theenclosed components through the mounting base 11 to the outside forconnection of the unit into the fluorescent-lamp starter circuit.

In the starter device shown in Fig. 4, the rectifier 4 together with theparallel connected thermistor forms an independent subassernbly which isput together with the starter subas'sembly to form a single unittherewith.

housing 27 at the outer periphery. The upper ends of the two springbodies 28, 29 are U-shaped so that they can readily be shoved over thehousing 12 of the starter switch subassembly. The over-all shape of thetwo spring bodies is adapted to the contour of the housing 12 when thesubassembly housing 27 and the housing 12 are ultimately joined witheach other. If desired, a mechanical connection can be provided betweenthe free ends of the spring bodies for improved reliability of theconnection. This is done in the illustrated embodiment by providing apull spring 30 between the respective ends of springs 28 and 29.

The top wall of housing 27 abuts against projections 27a of the starterhousing 12. Located in the interior of housing 27 are the rectifierelement and the thermistor 26, both shown schematically. The rectifierhousing 27 is provided with two through-channels formed of respectivesleeves 31 and 32 that are traversed by the respective connecting wires13 and 14 of the starter switch. The sleeve 31 consists of insulatingmaterial. The sleeve 32 consists of metal. The rectifier element 17enclosed in housing 27 and the likewise enclosed thermistor 26 have oneof their respective terminals electrically connected with the metalsleeve 32. The sleeve 32 is electrically connected with the connectingwire 14 of the starter switch by means of a soldered joint located atthe lower end of sleeve 32. Another connecting wire 33 ex tends out ofhousing 27 and is connected to the second terminal of the rectifierelement 17 and to the second terminal of the thermistor '26 within thehousing 27.

In analogy to the circuit diagram of Fig. l, a capacitor 9' is connectedacross the gap of the starter switch. If desired, the capacitor 9' canbe designed as an individual subassembly to be joined with the compositedevice mechanically and electrically to form a single unit therewith.

It will be obvious to those skilled in the art that with respect todetails of design and arrangement, a starter device according to myinvention can be modified in various respects and hence may be embodiedin devices other than particularly illustrated and described herein,without departing from the essential features of my invention and withinthe scope of the claims annexed hereto.

I claim:

1. A control device for fluorescent-lamp starting cir cuits, comprisinga glow-discharge switch thermo-responsive for closing its contacts dueto heating by glow discharge, a rectifier diode connected in series withsaid switch, said switch and said rectifier being joined together toform a single structural unit, and said unit having external electricconnection means electrically interconnecting said switch and saidrectifier and adapted for connecting said unit as a whole into the lampstarting circuit.

2. A control device for fluorescent-lamp starting circuits, comprising aglow-discharge switch thermo responsive for closing its contacts due toheating by glow discharge, a rectifier diode connected in series withsaid switch, an envelope structure in which both said switch and saiddiode are mounted to form a single structural wiring component, andelectric circuit connections interconnecting said switch and said diodewithin said envelope structure and extending to the outside forconnecting said component as a single unit into the lamp startingcircuit.

3. In a fluorescent-lamp starting device according to claim 2, saidenvelope structure having a single sealed space in which both saidswitch and said diode are mounted.

4. In a fluorescent-lamp starting device according to A claim 2, saidenvelope structure having two gas-tight claim 2, said envelope structurehaving two gas-tight chambers sealed from each other, a glow dischargeatmosphere in one of said chambers, an inert atmosphere in said otherchamber, said switch being mounted in said one chamber and said diode inthe other chamber.

6. In a fluorescent-lamp starting device according to claim 2, saidenvelope structure having a sealed space in which both said switch andsaid diode are mounted, said diode having a semiconductor member andhaving a p-n junction emerging at the surface of said member, and aninsulating coating on said member covering said p-n junction on saidsurface to prevent glow discharge at said member.

7. A control device for fluorescent-lamp starting circuits, comprising aglow-discharge switch thermo-responsive for closing its contacts due toheating by glow discharge, a rectifier diode connected in series withsaid switch, said switch and said diode having respective sealedhousings and being fixedly mounted therein to form respectivesubassemblies together therewith, said two subassemblies being mutuallyengageable and having fastening means for joining them mechanically andelectrically to form a single unit, said unit having outwardly extendingelectric conductors for connecting said unit as a single component inthe lamp starting circuit.

8. A fluorescent-lamp starting device according to claim 7, comprising athermistor electrically connected in parallel to said diode and mountedin said diode housing to form part of said diode subassembly.

9. In a control device according to claim 7, said fastening meanscomprising elastic latch members secured to said housing of said diodesubassembly and engageable with the other housing for latching said twosubassemblies together when said subassemblies are being joined.

10. In a control device according to claim 7, said housing of saidswitch subassembly having electric connecting leads attached to saidswitch and extending at one side of said latter housing to the outsideand away from said latter housing, and said diode subassembly havingchannels traversed by said respective conductors when said twosubassemblies are joined together.

11. -In a control device according to claim 10, said diode subassemblyhaving electric connecting leads attached to said diode and extending tothe outside of said diode housing.

12. In a fluorescent-lamp starting device according to claim 2, saidenvelope structure having two gas-tight chambers sealed from each otherin which said switch and said diode are mounted respectively, and athermistor connected in parallel to said diode and mounted in the samechamber as said diode.

13. A fluorescent-lamp starting device according to claim 2, comprisinga capacitor connected in parallel to said switch and joined with saidenvelope structure to form part of said single unit.

14. A fluorescent-lamp starting device according to claim 7, comprisinga capacitor connected electrically in parallel with said switch andbuilt together with said diode subassembly to form part thereof.

No references cited.

